[PENHALLOW] NORTH AMERICAN SPECIES OF DADOXYLON 88 
stances so delayed it as to prevent me from completing it during the 
life-time of Sir William Dawson, and thereby receiving the co-operation 
and advice of one who had so closely identified himself with these plants. 
In the course of my work I have endeavoured to take a complete 
survey of the literature of the subject. This has not been possible in 
the fullest sense, since one or two of the more important works have not 
been accessible. In nearly all cases, however, statements have been 
verified by direct reference to the original publication, and it thus be- 
comes possible to give a more extended and complete bibliography of 
the genus and of the individual species than has previously appeared. 
A detailed historical summary in this connection is rendered un- 
necessary by the presentation given by Knowlton, who clearly states the 
historical basis on which our present views rest.! But a brief résumé 
of the principal phases in our knowledge relating to this interesting 
group of plants, may serve to bring out somewhat more clearly, the 
bearings of the present discussion. 
Our knowledge of those plants which have been variously known 
among others, by the names of Dadoxylon, Cordaites, Cordaioxylon, 
Araucarites, Araucarioxylon commenced in 1833 with a description of 
several species of Pinites by Witham. In 1847, Endlicher described 
fourteen species of these plants under the name of Dadoxylon. <A re- 
cognition of the now well known Araucarian structure of the stem, 
led Pres] to adopt the name of Araucarites, which was subsequently 
changed to Araucarioxylon by Kraus and in a restricted sense, is still 
retained. In 1850, Unger applied the name Cordaites to certain leaves 
from the Paleozoic formation, and a few years later Geinitz was able 
to bring under the same designation, various parts of plants which had 
hitherto been assigned to several separate genera, but which he recog- 
nised as belonging to Cordaites. Grand Eury’s investigations of the 
Carboniferous of the Loire, led to most important results. The great 
abundance of material which he was able to collect, and the often per- 
fect state of its preservation, joined to the studies which Brongniart 
had already made of the silicified seeds from St. Etienne, permitted 
him to obtain a most complete history of Cordaites. Among other im- 
portant results reached, he was able to prove that the Cordaiteæ were 
gymnospermous plants, and that the problematical Artisia or Stern- 
bergia, which had for so long been a puzzle to palæobotanists, was noth- 
ing more nor less than the pith of Cordaites, In the meantime, how- 
ever, Williamson in England had shown that Sternbergia pith belonged 
to plants with an Araucarian type of structure, while Dawson in Canada, 
1 Proc. U. S. Nat. Mus., 1890, XII., 601. 
